Usually, a pilot controls a yawing movement of an aircraft running along the ground by acting on controls (the pedals of a rudder bar, a control wheel, etc.). In the case of an aircraft that has at least landing gear with a steerable bottom part bearing wheels, the controls act directly, through a controller that is dependent on the speed of the aircraft, on the steerable bottom part.
The thesis entitled “Automatisation du pilotage au sol pour la navigation portuaire [Automation of ground steering for port navigation]”, written by Mr. Jean DUPREZ for Airbus France—LAAS in 2004 (accessible through the on-line thesis website http://tel.archives-ouvertes.fr/) discloses how to modify the controller in order to provide the pilot with greater assistance in controlling the yawing movement. The thesis thus describes the following method:
on the basis of a command generated by the controls, determining a prepositioning angle through which to steer the wheels of the bottom part of the landing gear;
using closed-loop control which as its input has the prepositioning angle and which generates a correction thereof;
steering the bottom part through a steering angle equal to the prepositioning angle from which the correction has been subtracted.